Posts Tagged: citrus

Citrus plants can be hosts for invasive pests. Knowing what pests are invasive and how to avoid them is an important part of nursery production. If you work in a citrus nursery, you play an important role in looking for invasive pests and protecting the nursery—and ultimately California's citrus industry—from invasion.

Your mission, should you choose to accept it, is to prevent invasive pests and their harmful impact to agriculture. When pests or diseases are new to an area, we call them invasive. Many of the laws that are in place for citrus are to prevent new pests and diseases from establishing.

Citrus nurseries that become infested with new pests may be quarantined until the infestation is gone, preventing the plants from being moved or sold. Sometimes it requires the plants to be destroyed. Sometimes it results in the loss of a business.

You might have heard of some these invasive pests in California citrus—diaprepes root weevil, light brown apple moth, and red imported fire ant. Some invasive pests are diseases carried by an insect such as citrus variegated chlorosis spread by glassy winged sharpshooter, brown citrus aphid in Florida and Mexico making citrus tristeza even more problematic, and huanglongbing spread by Asian citrus psyllid.

Learn more about these invasive pests and how to stop their invasion by viewing an online training for workers of citrus growing in protective structures by UC Cooperative Extension Specialist Beth Grafton-Cardwell. Citrus Nursery Protective Structure Worker Training provides information on growing healthy citrus plants in structures and protecting them from common insect pests and diseases, including invasive ones in Chapter 3. You can also find on UC IPM's online training webpage, training about Asian citrus psyllid and huanglongbing for retail nursery personnel and for UC Master Gardeners.

When pests first arrive in California, an effort is made to detect them by searching the plants and by trapping them. It is important for you to be a detective and help in this effort:

Watch for anything unusual and report anything new.

Keep yourself and anything you work with in the protected structure clean, disinfected and free of pests.

Keep the protective structure sound by fixing holes in screens, gaps in the structure, and unprotected vents.

Use good practices in the nursery such as planning your day to start indoors and finish outdoors so that you don't bring outdoor pests inside.

During the week, spend your lunch with us learning the latest about invasive tree killing pests, aquatic nasties like quagga mussels and nutria, and how the invasive weed/wildfire cycle is altering our ecosystems!

Native to Asia, the Asian citrus psyllid, Diaphorina ciri, was first detected in the United States in June 1998 in Palm Beach County, Florida. Since then, ACP has invaded all other US citrus areas. It has been detected in 26 of California's 58 counties. Infected psyllids can transmit the bacterium Candidatus Liberibacter asiaticus, which causes the fatal citrus disease Huanglongbing (HLB). HLB is currently the most devastating threat to the worldwide citrus industry. A citrus tree infected with HLB may not exhibit any symptoms for two years, and will usually die within five years. UC ANR IPM states that there is no known cure. “The only way to protect trees is to prevent spread of the HLB pathogen in the first place, by controlling psyllid populations and removing and destroying any infected trees.”

The California Department of Food and Agriculture (CDFA) has set up extensive monitoring and quarantine programs to track and try to slow the spread of the insect and disease. Currently, both residential and commercial sites that have citrus are monitored by checking yellow sticky traps. Psyllid and leaf samples are being tested for the presence of HLB.

If ACP is detected in an area, farmers must resort to regular spray programs to try to control the ACP population. This practice negatively impacts efforts to have a citrus crop grown with IPM strategies that rely on beneficial insects. In a ground-breaking discovery encompassing six years of research, an international team of scientists led by UC Davis chemical ecologist Walter Leal announced they've identified the sex pheromone of ACP. This pheromone can be used to attract more ACP to sticky traps. “Having a [pheromone] lure to dramatically improve captures of this psyllid with the conventional sticky traps is a major progress toward [developing] integrated pest management [strategies],” said Professor Jose Robert Parra of the University of Sao Paulo. Read more.

Postdoctoral researcher Bodil Cass will speak on "The Ecoinformatics and the Curious Case of Katydids in California Citrus" at a seminar on Oct. 25 at UC Davis. Here's a photo of the fork-tailed katydid, Scudderia furcata, that she studies. (Photo by Bodil Cass)

Postdoctoral researcher Bodil Cass will speak on "The Ecoinformatics and the Curious Case of Katydids in California Citrus" at a seminar on Oct. 25 at UC Davis. Here's a photo of the fork-tailed katydid, Scudderia furcata, that she studies. (Photo by Bodil Cass)

In this image, fork-tailed katydids are all over citrus as part of a research project by postdoctoral scholar Bodil Cass of the Jay Rosenheim, UC Davis. (Photo by Bodil Cass)

In this image, fork-tailed katydids are all over citrus as part of a research project by postdoctoral scholar Bodil Cass of the Jay Rosenheim, UC Davis. (Photo by Bodil Cass)

Alireza Pourreza, a newly appointed UC Cooperative Extension agricultural engineering advisor at Kearney Agricultural Research and Extension center, has been awarded the 2016 Giuseppe Pellizzi Prize by the Club of Bologna, an honor presented every other year to the best doctoral dissertations focused on agricultural machinery and mechanization. The Club of Bologna is a world taskforce on strategies for the development of agricultural mechanization.

Pourreza, who earned his Ph.D. at the University of Florida in 2014, worked on early detection of Huanglongbing (HLB) disease of citrus. HLB, an incurable disease that is spread by Asian citrus psyllid (ACP), has seriously impacted citrus production in Florida. The disease has been found in commercial and residential sites in all counties with commercial citrus. Read more.